The nervous system Flashcards
What are the components of the nervous system?
The nervous system consists of the brain, spinal cord, nerves, sensory and motor nerves.
What does the peripheral nervous system consist of?
Nerves that branch out from the brain and spinal cord.
Give the meaning of nerves
Bundle of neurons
Give the meaning of neurons
Nerve cells
Give the meaning of a nerve impulse
Electrical signal that transmits along a neuron
What following features do motor neurons have?
Dendrites: make connection with other neurons
Cell body that contains a nucleus and other organelles
Axon: carries nerve impulse from body cell
What is myelin sheath?
Consists of Schwann cells and specialized cell wrapped around the axon
What is the small gap called between the Schwann cells?
Nodes of Ranvier
What does the combination of myelin sheath and Nodes of Ranvier increase?
The rate at which the nerve impulse travels along the axon
When the axon branches, what does it form?
Axon endings or terminals that makes connections with motor or sensory neurons
Sensory neurons carry —– ——– from receptors that act’s as a —- ——- towards the —
nerve impulses
body sensors
CNS
Give the functions of nerve systems
Sensory neurons carry nerve impulse from receptors that acts as a body sensor towards the CNS.
CNS takes information contained in inputs from the sensory neuron and processes it
Sends nerve impulses via motor neurons to effector organs.
What are nerve impulses?
Electrical signals transmitted from the cell body towards the axon terminals
What happens when a neuron is at rest?
There is a small potential difference across the plasma membrane of around -60MV
Phase two of synaptic transmission
The inside of the neuron becomes slightly more negative than the outside due to positive Na+ ions which have been pumped out of the neuron
Phase three of synaptic transmission
Polarization of the plasma membrane is described as resting potential.
Phase four of synaptic transmission
Nerve impulses involves a rapid change in the membrane potential, the membrane becomes depolarized so the inside is slightly more positive compared to the outside.
Phase five of synaptic transmission
Process is rapidly reversed in a few milliseconds and becomes repolarized known as action potential
Phase six of synaptic transmission
AP is propagated or transmitted along the axon and represents a nerve impulse
Phase seven of synaptic transmission
Motor neurons are known as myelinated because they have myelin sheath, therefore AP jumps from one Node of Ranvier to the next.
What are the connections between neurons called?
Synapses
Why is transmission of a nerve impulse across a synapse not possible?
Because there is a gap.
What is the nerve impulse carried across the synapse by?
Neurotransmitters
Give the meaning of polarisatiom
Different electrical charges on either side of the plasma membrane caused by active transport of ions.
Give the meaning of depolarisation
Reversal of charge difference
Give the meaning of repolarisation
Restoration of orginal charge difference
Role of synaptic knobs
Makes connection with muscles or another neuron.
When a nerve impulse arrives at a synaptic knob, what occurs after?
It releases neurotransmitters from the membrane-based vesicles
Give the most common neurotransmitter
Acetylcholine
What is a reflex action?
Automatic response to an external stimulus
Why is a reflex action important?
It helps to minimize injuries and it is thought of as a survival response.
What happens when a stimulus e.g. heat is detected?
It is detected by the receptors in the skin and branches off the end of the sensory neuron which transmits a nerve impulse to spinal cord.
Sensory neuron then makes a synapse with a relay neuron which makes a synapse with a motor neuron.
The motor neuron then conducts nerve impulses to arm muscle causing it to contract.
What is Parkinson’s disease?
A disease that causes a loss of neurons in the substania nigra and the neurons that are lost release dopamine.
Neurodegenerative disease.
What does dopamine do?
It is involved in regulating movement in the body and the loss of dopamine makes it responsible for symptoms.
How can Parkinson’s directly impact the body physically?
- Involuntary shaking of the body creating a tremor
- Slow movement
- Stiff and inflexible muscles
Give some psychological symptoms of Parkinson’s
Anxiety and depression
Balance problems
Insomnia
Anosmia (loss of smell)
Memory problems
Give some treatments for Parkinson’s
Physiotherapy
OT
Levodopa medication
Surgery
Physiotherapy treatment
Improves balance and posture
Strengthens muscles
Increase flexibility
Occupational Therapy
Makes difficult tasks easier
Equipment or gadgets for practical changes
Levodopa medication
Helps replace lost dopamine
Can cause dramatic improvement at first but then can decrease over time.
Give some side effects of Levodopa
Tiredness, sickness and dizziness
Give some long-term side effects of dyskinesia
Uncontrollable jerk movements
Surgery
Deep brain stimulation which involves inserting a fine wire into the brain and inserting a permanent electrode and attaching it to a pulse generator.
What does deep brain stimulation do?
It delivers high electrical impulses to improve symptoms
Give a risk of having surgery
Stroke
